The present invention relates to tube cleaning and particularly to propelling foam pellets by compressed air through hydraulic hose, tubes, piping, conduits and the like for cleaning interior surfaces.
Compressed air propelled foam pellets or projectiles are used for cleaning the interior surface of a variety of conduits including hydraulic and pneumatic lines wherein the foam projectile removes particulate matter, wipes the interior wall, and absorbs surface film. The projectile outer diameter is greater than conduit bore diameter for effective cleaning of the interior wall with the projectile being propelled by compressed air. The projectile acts as a seal against the interior wall such that the full force of the compressed air acts to move the projectile through a conduit. Foam projectiles are available in a range of diameters for use in cleaning conduits in a corresponding range of diameters.
Hand held pneumatic guns of the type described in U.S. Pat. No. 4,974,277 are used to position a projectile for entry into a conduit, and to propel the projectile through the conduit with compressed air. A pneumatic gun of this type includes interchangeable nozzles in different sizes to accommodate different size projectiles for application over a range of conduit diameters.
The pneumatic gun includes a pivoting breech ring for interchanging nozzles and for hand loading projectiles one-by-one into the nozzle. In a first position the breech ring pivots open for breech loading of a projectile into the gun nozzle. The breech ring is then closed manually. By positioning the gun muzzle adjacent a conduit opening and pulling the trigger, a compressed air charge propels the projectile through the conduit. When the projectile passes through the conduit, the compressed air charge is completely dissipated. This loading and firing sequence is repeated for each projectile loaded into the pneumatic gun.
The steps of opening and closing an pneumatic gun breech for each projectile adds to the complexity and time consumed for completing a conduit cleaning work schedule.
In the event a conduit is obstructed or blocked and the projectile travels into and not through a conduit, the compressed air charge is not dissipated and acts both to force the blocked projectile and to force the air gun away from the conduit opening. The potential for obstructed conduits presents a safety hazard for an air gun operator and creates a need for dissipation of compressed air charges in these circumstances.
The present invention provides a new and improved air gun for cleaning the interior wall of various kinds of conduits utilizing compressed air propelled projectiles.
In a preferred embodiment of the invention, a pneumatic air gun for conduit cleaning with foam projectiles comprises a hand grip with actuating trigger, projectile loading chamber with a quick load port, a nozzle, and a compressed air circuit including an air flow control valve for directing air in propelling a projectile and for dissipating an air charge in the event of a conduit obstruction.
In one aspect of the invention, a projectile loading chamber surmounts the gun""s handgrip and includes a quick load port through which projectiles are loaded into a nozzle fitted to the front of the projectile chamber. A door or port closure member is spring biased to normally closed position over the port. For loading the gun, foam projectiles are pushed through the port closure into a nozzle with the closure then returning to closed position. The interior of the chamber, as well as the nozzle interior behind the projectile then receive a compressed air charge when the trigger is pulled. Compressed air propels the projectile through a conduit cleaning its interior wall. Another projectile is then loaded and fired in this way. The nozzles are interchangeable for a range of nozzle diameters and projectiles for cleaning conduits in a corresponding range of diameters.
In another aspect of the invention, compressed air flows from a source through the gun""s handgrip and through a trigger actuated air flow control valve into the gun chamber. In the event pressurized air remains in the gun chamber after firing a projectile by reason of an obstructed conduit, the air pressure is dissipated through the air flow control valve when the operator releases the trigger. The built-up compressed air then is diverted harmlessly through an exhaust circuit opened as the trigger is released. Trigger release also stops compressed air flow into the gun chamber.
The present invention, then, provides a quick loading pneumatic gun for propelling tube cleaning projectiles by compressed air with a safety circuit for harmlessly dissipating any compressed air build-up in the event of an unexpected tube blockage.
A specific example is included in the following description for purposes of clarity, but various details can be changed within the scope of the present invention.
An object of the invention is to provide a pneumatic gun for quickly loading and firing conduit cleaning projectiles.
Another object of the invention is to provide a pneumatic gun for quickly loading and firing conduit cleaning projectiles in which foam projectiles are loaded into a gun chamber through a port directly into a positioning nozzle and fired by a compressed air charge.
Another object of the invention is to provide a pneumatic gun for quickly loading and firing conduit cleaning projectiles by means of compressed air with a compressed air relief circuit for dissipating pressurized air in the event of failure of a projectile to pass through a conduit.
Another object of the invention is to provide a pneumatic gun for quickly loading and firing conduit cleaning projectiles by means of compressed air supplied through an air flow control valve which directs air for propelling projectiles and which directs pressurized air to ambiance in the event of failure of a projectile to pass through a conduit.
Other and further objects of the invention will become apparent with an understanding of the following detailed description of the invention or upon employment of the invention in practice.